Edit (11/17/20): seems they have fixed this achievement and it should still be obtainable in private matches
This can be obtained in private matches currently
Simple achievement: basically stand in the hill as much as possible. easier with a second controller but could be done with bots
Setup:
Versus --> Custom --> Online Game --> Host Private --> Game Setup --> Arcade Blitz for game type --> Arcade Blitz game options --> fill with bots 'no' (easier) I had round score set to 200 but I would assume you could set it at 50 --> have a second controller and assign to other team --> go stand in the hill and get all the points